Assessing and Mitigating the Risks for Polio Outbreaks in Polio-free Countries — Africa, 2013–2014

McKenzie Andre, MD; Chris G. Wolff, MPH; Rudolf H. Tangermann, MD; Paul Chenoweth, ND; Graham Tallis, MBBS; Jean Baptiste Kamgang, MS; Steven G.F. Wassilak, MD


Morbidity and Mortality Weekly Report. 2014;63(34):756-761. 

In This Article

Abstract and Introduction


Since 1988, when the Global Polio Eradication Initiative (GPEI)* began, the annual number of polio cases has decreased by >99%.[1] Only three countries remain that have never interrupted wild poliovirus (WPV) transmission: Afghanistan, Nigeria, and Pakistan.[1] Since 2001, outbreaks have occurred in 31 formerly polio-free counties in Africa, with outbreaks in 25 countries caused by WPV originating in Nigeria.[2–4] After the declaration of the World Health Assembly of polio eradication as a programmatic emergency in 2012, efforts to identify areas at high risk for importation-associated outbreaks and to reduce that risk have been intensified.[5] This report updates the 2013 assessment of the risk for outbreaks attributable to importation of poliovirus in 33 countries in Africa, using indicators of childhood susceptibility to poliovirus and proximity to countries currently affected by polio.[6] From January 2013 to August 12, 2014, outbreaks occurred in five African countries. Four of the five (Cameroon, Equatorial Guinea, Ethiopia, and Somalia) have had recent transmission (cases within the previous 12 months). Based on the current risk assessment, 15 countries are considered to be at high risk for WPV outbreaks, five at moderate-to-high risk, seven at moderate risk, and six at low risk. In 15 of the 33 countries, less than half of the population resides in areas where surveillance performance indicators have met minimum targets.[7] Enhanced, coordinated activities to raise childhood immunity are underway in 2014 to prevent additional WPV spread. Although substantial progress toward polio eradication has occurred in Nigeria, all African countries remain at risk for outbreaks as long as WPV continues to circulate anywhere on the continent.

* The Global Polio Eradication Initiative is a public-private partnership led by national governments and led by the World Health Organization, Rotary International, CDC, and the United Nations Children's Fund (UNICEF). Additional information available at